Vulnerability of motorcycle riders and co-riders to injuries in multi-occupant crashes.

In developing countries, most motorcycles are ridden with more than one occupant. The objective of this study was to establish the relative vulnerability of riders and co-riders to injury and determine the injury risk factors in multi-occupant motorcycle crashes. Between January and December 2010, we collected crash and injury data from victims of multi-occupant motorcycle. It is a hospital-based study. The probability of sustaining injuries was similar for co-riders and riders, but co-riders were more likely to sustain severe injuries. Occupants of >2-occupant motorcycles were also more likely to be involved in risky behaviours like not wearing helmet and speeding than those on 2-occupant motorcycles. Occupants of motorcycles on which there were more than two occupants were at an increased risk of sustaining injuries compared with occupants of motorcycles with only two occupants (OR: 2.1, 95% CI: 1.1-4.3). Motorcycle co-riders were more vulnerable to severe injuries than riders. The significance of the study finding to prevention was discussed.